resolve review comments

Author: gty404

src/iceberg/table_metadata.cc

@@ -41,6 +41,10 @@
 
 namespace iceberg {
 
+namespace {
+const TimePointMs kInvalidLastUpdatedMs = TimePointMs::min();
+}
+
 std::string ToString(const SnapshotLogEntry& entry) {
   return std::format("SnapshotLogEntry[timestampMillis={},snapshotId={}]",
                      entry.timestamp_ms, entry.snapshot_id);
@@ -224,7 +228,7 @@ struct TableMetadataBuilder::Impl {
   explicit Impl(int8_t format_version) : base(nullptr), metadata{} {
     metadata.format_version = format_version;
     metadata.last_sequence_number = TableMetadata::kInitialSequenceNumber;
-    metadata.last_updated_ms = TableMetadata::kInvalidLastUpdatedMs;
+    metadata.last_updated_ms = kInvalidLastUpdatedMs;
     metadata.last_column_id = Schema::kInvalidColumnId;
     metadata.default_spec_id = PartitionSpec::kInitialSpecId;
     metadata.last_partition_id = PartitionSpec::kInvalidPartitionFieldId;
@@ -448,7 +452,7 @@ Result<std::unique_ptr<TableMetadata>> TableMetadataBuilder::Build() {
   // 2. Validate metadata consistency through TableMetadata#Validate
 
   // 3. Update last_updated_ms if there are changes
-  if (impl_->metadata.last_updated_ms == TableMetadata::kInvalidLastUpdatedMs) {
+  if (impl_->metadata.last_updated_ms == kInvalidLastUpdatedMs) {
     impl_->metadata.last_updated_ms =
         TimePointMs{std::chrono::duration_cast<std::chrono::milliseconds>(
             std::chrono::system_clock::now().time_since_epoch())};

src/iceberg/table_metadata.h

@@ -73,7 +73,6 @@ struct ICEBERG_EXPORT TableMetadata {
   static constexpr int64_t kInitialSequenceNumber = 0;
   static constexpr int64_t kInvalidSequenceNumber = -1;
   static constexpr int64_t kInitialRowId = 0;
-  static constexpr TimePointMs kInvalidLastUpdatedMs = TimePointMs::min();
 
   /// An integer version number for the format
   int8_t format_version;